Peritoneal dialysis systems provide for the cycling of dialysis fluids through a patient's peritoneum. The cycling process includes pumping fresh fluid into the peritoneal cavity as well as removing spent fluid after a predetermined time interval. Electrically controllable valves which will reliably open and close paths for the fluid flow are often needed in such dialysis systems.
In view of the fact that patient treatment is involved, the fluids involved are sterile and the occlusion devices or valves must not come in contact with the fluid. Separation of the valve mechanism from the fluid is conventionally accomplished by using flexible sterile tubing through which the fluid can be permitted to flow or be pumped and which can be pinched closed by an appropriate apparatus. Such an apparatus is disclosed in U.S. Pat. No. 4,397,642 entitled "Motor Driven Occlusion Controller For Liquid infusion And The Like." The occlusion apparatus disclosed in this patent incorporates a stepping motor in combination with a clamping member which moves in a curvilinear direction under the control of the stepping motor to unclamp a tube through which fluid is to flow. This occluder valve is designed to automatically close subsequently by means of a spring member thereby pinching the tubing closed.
Alternately, solenoid actuators could be used to provide an electrically controllable valve, which can be opened in response to an applied electrical signal and which will close due to spring loading upon removal of the electrical signal.